Age Is Not a Factor in Immunity to Viruses, as Previously Assumed

Our immune system does not shut down with age, says a new study by immunologists at Toronto’s McMaster University, U-Toronto and U-Penn - likely explaining poor performance of flu vaccines tailored for older adults

A study published Dec 13 by PLoS Pathogens demonstrated that a specialized class of immune cells, known as T cells, can respond to virus infections in adults at age 60-plus with the same vigor as T cells from a young person. See the full text here.

“For a long time, it was thought the elderly were at a higher risk of infections because they lacked these immune cells, but that simply isn’t the case. The elderly are certainly capable of developing immunity to viruses,” says McMaster Prof. Jonathan Bramson, PhD, the principal investigator.

The researchers examined three groups of individuals (younger than 40; middle-aged, between 41 and 59; and older than 60) - infected with three different serious viruses:

• West Nile virus

• Cytomegalovirus, and

• Epstein-Barr virus…

…and found the older group demonstrated perfectly normal immune responses.

No Thinning of Ranks, No Loss of Fight

Both the number of virus-fighting T cells and the functionality of the T cells were equivalent in all three groups.

“So as we age, our bodies are still able to respond to new viruses, while keeping us immune to viruses we’ve been exposed to in the past,” Dr. Bramson says.

The discovery also suggests that use of T-cell activating vaccines (e.g., for flu) may significantly boost protection for older adults.

These results have important implications for vaccination of mature adults, Dr. Bramson emphasizes. Currently, for example, the flu vaccines recommended for older patients are not designed to elicit responses from these immune T cells – potentially explaining why the vaccines haven’t seemed to afford much protection.

That is, vaccines specifically designed to generate T-cell immunity may be more effective at protecting older adults - with live vaccines being the platforms of choice, Dr. Bramson says.

The research was funded by the Canadian Institutes for Health Research and the U.S. National Institutes of Health. PLoS Pathogens is an open-access, peer-reviewed journal of the Public Library of Science.